Conventionally, a technique for displaying signal sequence information of a subject traffic signal beyond a scope of a current signal sequence that can be viewed by a driver who is heading for an intersection having the subject traffic signal is disclosed, for example, in Japanese patent documents JP-A-2006-155319 and JP-A-H11-272992.
In the disclosure of the above patent documents, a technique addresses a problem regarding a right turn at an intersection in the left-side traffic system (a right-left relationship may be reversed for the right-side traffic system). The addressed problem is that, when a driver of a vehicle is waiting for a right turn at a center portion of the intersection, he/she in wait fails to notice a change of traffic signal from allowing the entrance into the intersection to not allowing for an on-coming traffic. In other words, when the driver fails to notice a transition of the traffic signal changing from Green to Red through Yellow, he/she may be left to a standstill at the center of the intersection, due to a loss of an appropriate right-turning timing.
The inventor of the present disclosure has noticed that, at some intersection, a right turn light disposed in a certain traffic signal for permitting right turning at the intersection (e.g., a right arrow shape light) is not lighted (i.e., is not turned on) after a change of the traffic signal from GO (i.e., Green light) to STOP (i.e., Red light) for a straight traffic that passes straight through the intersection. That is, in this case, an expected signal sequence is different from the actual sequence.
In the above intersection, the possibility of a vehicle to enter the intersection having an expectation and a hasty conclusion of the driver that the traffic signal sequence currently changing from GO to STOP for the straight traffic is followed by the right turn light being turned on in the next signal sequence for allowing/permitting the right-turning of the vehicle is increased, with the vehicle brought to a standstill at the center of the intersection while attempting the right turning in vain.